1. Field of the Invention
The invention generally relates to recording and/or reproducing apparatus for use with a flexible storage medium, such as a non-rigid disk. More particularly, the invention relates to a stabilizer device supported in relation to a magnetic head for maintaining an effective interface between the head and a magnetic storage medium.
2. Description Relative to the Prior Art
Magnetic recording and playback relative to a pliant, "floppy" magnetic disk requires that a constant interface be maintained between the moving disk and a magnetic record/playback head. The stability of the interface typically depends upon an air bearing effect. Further stability is obtained by interposing the magnetic disk between the head and a pressure-exerting backing member that forces the disk to conform to the head. For contact recording, the magnetic disk is brought into effective contact with the magnetic head. In practice, a small film of air, typically a few microinches, may actually be interposed between the head and the surface of the magnetic disk during contact operation. Many factors, such as fluttering at high speeds, may change the spacing and the stability of the interface between the disk surface and the magnetic head.
U.S. Pat. No. 4,578,727 discloses that the interface in a contact system may be stabilized by surrounding the transducing surface of the magnetic head with a small, flat air bearing surface. The head is supported in relation to an opening in the air bearing surface to a negative pressure cavity. When the disk is rotated at relatively high speeds, a negative pressure is formed in the cavity that pulls a nearby section of the rotated disk into contact with the transducing surface of the head thereby ensuring a constant interface for effective magnetic coupling. In companion U.S. Pat. No. 4,620,250, the air bearing surface is disposed at an angle with respect to the disk medium so that a leading edge of the air bearing surface penetrates slightly into the nominal plane of the rotating disk, thus "scraping" air away from the surface and "choking" off the flow of air over the air bearing surface. This is believed to assist in the formation of strong coupling forces along the air bearing surface. With both patents, magnetic coupling is effected without the necessity of opposing the air bearing surface with a backing member.
Nonetheless, it is difficult to continuously stabilize the magnetic interface if there is any irregularity inherent in the medium forming the disk, especially an irregularity due to a "warp" or like deformation in the medium. It has been found that virtually undetectable deformations are present in a wide variety of otherwise acceptable disks, particularly in a disk of the type having a central hub that is fastened to the disk. The presently known stabilizers are ineffective in consistently "capturing", that is, establishing an interface with, the surface of such irregular disks. Either the recovered signal drops off unacceptably, e.g., by more than 3db, or head/disk contact cannot be maintained for a full revolution of the disk, i.e., signal dropouts occur.